- .. - MORDIALLOC CREEK Environmental Strategy and Opportunities Report Prt:part:d by Dandenong Valley WaterwaysAdvisory Committee ..fag ;; • DRAFT MORDJAL LOC CREEK En vironmental Strategy and OpportunitiesR epon Pro duced for Public Comment by the Dandenong Valley Wate,ways Advisory Committee September_1 992 Comments on this reportsh o uld be forwarded to: Dandenong Valley Waterways A dvisory Committee PO Box 550 DA NDENONG 3175 by 18 November 1992 ------·· • The oandenong Valley Wate::-...tays Advisory Committee was for:ned in 1990 to advise the Hinis-ee.:- for Water I ! Resources on progress bei.ng made to achieve wate.:­ quality st·andards and other objectives p::-oposed by the State Environment Protection ?olicy for the Wate::-s of the Dandenong Va.lley. M embership of the Commi.t':ee includes representatives of: oe�a::-t:nent of Conservation & Envi.:-o��ent Deoar<:ment of Water Resources Helbou::-ne Water En·,..ironment Protection Authority City of Kordialloc City of Chelsea City of frankston City of Springvale toget:1er with The Hon. Hal Sanden, MP The Hon. Peter Spyker, MP A Community Representative Table of Contents Page Synopsis l l. Background 2 2. Ti.m.i.og 4 3. Kxisting Conditions s 4 • .. Objectives • Principles ·, 5. Opportunities " Constraints 10 6. Elements of the Concept 11 7. Impleme!1tation Opportunities 14 8. The Next Step 22 Figures -- 1. Zones and Reserved Land 3 2. Kordialloc Creek catchment 7 3. Wetlands of the Lower Dandenong Valley 18 Foldout Illustrations - Waterway G Wetland Enhancement Opportunities following 22 - l - SYNOPSIS The Draft Environmental Strategy presented here outlines the opportunities for the remodelling of Moi;:slialloc Mai_�a.in__ ��o� __ .Pillars Crossing to Wells Road. The plan proposes earthworks and planting to change the shape of the levees and waterway from the existing straight course to a more interesting, "natural" form. There is a significant opportunity to create a series of wetlands along the Creek. Reed beds within the wetlands will help to filter out sediments and pollutants, thus improving the quality of water entering Mordialloc Creek and Port Phillip Bay. The strategy has five main aims:- l. To improve the quality of water and reduce the amount of sediment entering the estuary. 2. To retain and improve the flood mitigation capability of the creek and floodplains. 3. To increase the amount and variety of habitat along the c:eek for local fauna and flora. .. 4. To enhance the quality of the local landscape • 5. To develop the creek as a place for recreation. The creation of a series of wetlands along Mordialloc Main Drain, which lies midway between Braeside Park and the Edithvale Wetlands, will consolidate the habitat and recreation importance of this region, making it a "habitat area" of truly international significance. The plans incorporated in this report present the ��-l_"_situation and may �\ be implemented over a long period of time. -rmplementation will be dependent on funding and on some land becoming available - by co-operative arrangements with landowners, by purchase where necessary, and by co­ ordinated sympathetic development. This document should form the basis for the preparation of a statutory concept plan under the Planning and Environment Act 1987. Such a statutory planning document would ensure that the objectives of the plan are considered in·any future town planning determinations for the area. This plan seeks to: flag to decision-makers and landowners the desirable future form of the parcels of land which make up the Creek and environs. enthuse the local and broader communities about the possibility for a better creek environs. Underpinning the plan are the principles of total catchment management and environmentally sustainable development. - 4 - 2. TlXING It is desirable that an environmental strategy for Mordialloc creek be prepared at this time as there are a number of matters that will be affected by the strategy. These include: a) a review of a portion of the "green wedge" in Keysborough is being carried out by the Department of Planning and Sousing in conjunction with the Cities of Oandenong and Springvale. The "green wedge" review area is the area surrounded by the Mornington Peninsula Freeway, South Eastern Purification Plant and the proposed Dingley and Scoresby Freeways. This review will investigate appropriate land ·1 uses for the area, identify major road, service, open space and , landscape linkages through the area and prepare landscape and design guidelines for critical locations. Amendment to the planning schemes covering the area may result. b) the need to decide what part the proposed Theme Park, .on the corner of Button and Springvale Roads, Keysborough is to play in the development of the Chain of Wetlands strategy. c) the need by Melbourne Water · and other agencies to develop total catchment management strategies for the improvement in quality of urban runoff and the control of trash and sediment reaching waterways, estuaries and Port Phillip Bay. - 5 - 3. EXISTING CONDITIONS 3.l Water QUality The water quality of Mordialloc Creek is dominated by urban runoff and the sewage effluent discharge from the Melbourne Water Dandenong treatment works. The table shows current water quality at various sites both upstream and downstream of Mordialloc Main Drain. In general, water quality at all sites exceeds State Environment Protection Policy criteria. The difference between values downstream of Mile Creek and at Pillars Crossing in Dandenong Creek indicate the degree of influence the Melbourne Water Dandenong treatment works discharge is having on the water quality in Dandenong Creek. Differences between values in Dandenong Creek downstream of Mile Creek (Melways 89Kl0) and those of the major drains entering Mordialloc Creek indicate the relative impact of these drain inputs. The elevated concentrations in Mordialloc creek at Wells Road are difficult to interpret and are probably an aberration of testing at this site being sampled less frequently (approx. 10 times over 2 years) than Dandenong Creek at Pillars Crossing or Mordialloc Creek at the Railway Bridge (approx. 30 times over 2 years). In general the results and water quality are similar to the most recent previous assessment by the Dandenong Valley Authority in 1990. The planned removal of Melbourne Water Dandenong treatment works effluent from the system before 1995 will significantly improve the water quality of Dandenong Creek and Mordialloc Creeks particularly with respect to nutrients, however significant concentrations of suspended solids and E. coli are likely to remain. These variables alone can significantly influence beneficial uses and water quality in the estuary and warrant the investigation of possible urban runoff treatment methods such as wetlands. KXDIAN VALUES * (July 1989 - January 1992) DO .K.co.l.i. 8005 SS Dandenong Creek 9.5 2.1 22.0 0.1 0.1 1400 downstream Mile Creek Dandenong Creek 8.5 8.7 21.0 2.3 2.9 2200 at Pillars Crossing (A) I Dunlops Drain 6.8 6.0 10.0 0.4 0.4 3200 downstream Governor Rd (8) Mordialloc Settlement 7.1 6.1 10.0 0.5 0.2 2500 Drain at Governor Rd (C) Mordialloc Creek 5.4 ll.O 28.0 2.5 7.0 3100 at Wells Rd (D) Mordialloc Creek 6.2 5.5 20.0 l. 7 2.0 2200 at Railway Bridge (E) State Environment >4.0 N .S. <25 N.S. N.S. <1000 Protection Policy W-28A Desirable Values >8 <5 <20 <0.l <0.l <1000 Onita: mg./1, except for E. coli - organisms/lOOml. • Where DO • Dissolved Oxygen, soo5 • Biochemical Oxygen Demand, SS • Suspended Solids, P04-P • Orthophosphate as Phosphorus, NH4-N = Ammonia as Nitrogen and N.S. • Not Specified. t For location refer to Figure 2. - 8 - An industrial subdivision has been filled and developed adjacent to Wells Road and west of Mordialloc Settlement Drain (Canterbury Road and Haymer Court), right down to the WAG pipeline. Similarly, a small area on Governor Road east of Dunlops Drain. The balance of the land is undeveloped and generally flood prone. The undeveloped land is held in two parcels, and development requirements have been set on both. The larger parcel of some 75 hectares had development requirements set in 1971, including the provision of a 300 foot (91.4 metre) drainage reserve adjacent to Mordialloc Creek. All of this land, including the proposed drainage reserve, is currently zoned industrial. The rest of the land up to Springvale Road south of Governor Road was previously zoned for farming and extractive uses but the 19 ha triangular portion west of the freeway has been recently rezoned garden industrial. A condition placed on this rezoning, which will result in filling, was that there was to be no further loss of flood storage on the balance of the land east of the freeway and that the drainage reserve was to be provided, as described above. On the triangular piece of land, the area between Mordialloc Creek and the WAG easement has been zoned stream and floodway. Further, negotiations on subdivision have resulted in a proposal for a l.65 hectare drainage reserve to cover an area of remnant swamp paperbark. A drainage scheme has been prepared for this section of creek and includes remodelling of the area between the WAG easement and Mordialloc Creek. Proposed Freeway to Springvale Road The existing creek has the same section here as downstream, that is, a. straight channel with high levees on either side. The northern· levee is unlikely to be overtopped and flooding mainly occurs through backing up from the Dunlops Drain/Mordialloc Creek confluence any future works should ensure that the flow path remains open so that the flood storage can be fully utilised. The floodplain north of the creek in this area has some 1,000,000 cubic metres of flood storage which has to be retained.